A person who chooses not to using or consume any animal products. This includes meat, dairy and eggs. They also avoid fur, leather, wool, down or any other material made from animals.
Most have strong tendencies towards protecting the environment and not causing harm to animals. Some vegans are strong advocates of promoting a cruelity-free and healthy lifestyle while others are not. But not all vegans are animal rights activities, as some are most focused on the health benefits. And evidence is mounting linking the consumption of animal fats and proteins to heart disease, colon and lung cancer, and osteoporosis to name a few. But this is still being debated and each side has research and case studies which support their case, respectively.
There is much opposition to this belief causing a heated debate on either side of the issue. Many people consider vegans to have a misplaced empathy towards animals and cite reasons why humans naturally should eat meat, for example, the fact human have canines, the pointy teeth used for tearing food.
Having canines, although, is not a conclusive reason as to why humans should eat meat. Gorillas, who are predominately herbivores, have both molars and canines. If having canines is an indicator of being a carnivore, then gorillas would be meat eaters. Rather then basing an argument on teeth, a better argument could be made for eating or not eating meat by examining the nutrients we need and how we can best get them.
Another argument against vegans are health concerns from cutting out two food groups from your diet. But this is a too literal interpretation of the food pyramid.
The "meat, poultry, fish, dry beans, eggs and nuts" group is necessary to get protein, B vitamins, iron and zinc. Soy bean, and hence tofu, are a good source of calcium, iron, B vitamins* and zinc. Getting B12 is a touchie subject as B12 is found primarily in meat, eggs and diary products, also there are plant sources. (B12 is created from bacteria after all). Fortunately the body needs a very small amount of B12. Soy products exist that are fortified with B12, thus meeting the required amount needed for the body.
The "milk, yogurt, and cheese" group provides protein, vitamins and minerals. Soy milk is a good source for protein, vitamins and minerals, and is also fortified with B12. There are other products which vegans can use to get their recommended values of nutrients.
However, vegans can be a risk of having vitamin and mineral deficiencies, if they have a poor diet. (Eating potato chips all day is vegan, but not health.) Therefore, it is important to understand what the body needs and how to get it, for vegans and non-vegans alike. So, as your mother would say, "eat your vegetables," but eat plenty of other stuff as well.
Veganism has roots dating back to 1909 when the ethics of consuming dairy was being debated. But the word vegan, which is taken from vegetarian was created in the United Kingdom in 1944 with the formation of the Vegan Society.